package io.gitee.wminyu.day07.Recursive;

import java.util.Scanner;

public class Sum {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int n = input.nextInt();
        System.out.print(sum(n));

    }
    public static int sum(int m){

        if (m==1){
            return 1;
        }else {
            return m+sum(m-1);
        }
    }
}
